Background/Aims: Mesenchymal stem cells from human amniotic fluid (huAFMSCs) can differentiate into multiple lineages and are not tumorigenic after transplantation, making them good candidates for therapeutic purposes. The aim was to determine the effects of calcitonin on these huAFMSCs during osteogenic differentiation, in terms of the physiological role of calcitonin in bone homeostasis. Methods: For huAFMSCs cultured under different conditions, we assayed: expression of the calcitonin receptor, using immunolabelling techniques; proliferation and osteogenesis, using colorimetric and enzymatic assays; intracellular Ca2+ and cAMP levels, using videomicroscopy and spectrophotometry. Results: The calcitonin receptor was expressed in proliferating and osteo-differentiated huAFMSCs. Calcitonin triggered intracellular Ca2+ increases and cAMP production. Its presence in cell medium also induced dose-dependent inhibitory effects on proliferation and increased osteogenic differentiation of huAFMSCs, as also indicated by enhancement of specific markers and alkaline phosphatase activity. Conclusions: These data show that huAFMSCs represent a potential osteogenic model to study in-vitro cell responses to calcitonin (and other members of the calcitonin family). This leads the way to the opening of new lines of research that will add new insight both in cell therapies and in the pharmacological use of these molecules.